The present invention relates to a medium transporting device for transporting a medium, and a recording apparatus incorporating such a medium transporting device.
Generally, in a large-size printer which is a well-known recording apparatus, a sheet feeding section for feeding a recording medium such as recording paper is disposed below a printer body. A recording section for recording information on the fed recording paper and a sheet ejecting section for ejecting the recording paper after recording are disposed above the printer body. When such a large-size printer, for example, an ink jet printer is used, a user places recording paper in the sheet feeding section so that a leading end portion of the recording paper is pulled out of the sheet feeding section. While the leading end portion of the recording paper is clamped between a feeding roller and a follower roller, the ink jet printer is activated.
As a result, the ink jet printer rotates the feeding roller to feed the recording paper to a nip portion between a transporting roller and a follower roller in the recording section through a transport guide member. Then, while a feeding roller is rotated to feed the recording paper onto a platen of the recording section, ink drops are jetted from nozzle orifices of recording heads of the recording section to record information on the recording paper. The feeding roller is further rotated to transport the recording paper to a nip portion between an ejection roller and a follower roller in the sheet ejecting section. Then, the ejection roller is rotated to eject the recording paper onto a tray (e.g. see Japanese Patent Publication No. 2002-254740A).
Each of the follower rollers provided in the ink jet printer is made of plastics. A metal shaft is inserted in each follower roller so that the follower roller rotates while sliding on the metal shaft. Accordingly, the friction coefficient between the follower roller and the shaft is relatively high, so that a large transport resistance is generated on the basis of a friction loss of the shaft caused by pressing force of the follower roller. For this reason, a slippage occurs when the recording paper is transported. Because the amount of the slippage varies according to the kind of the recording paper, it is difficult to correct the transporting amount while considering the slippage for all kinds of recording paper.